dotnet · davkean · Aug 28, 2026
@@ -0,0 +1,7 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Runtime.CompilerServices;
+using Microsoft.Internal;
+
+[assembly: InternalsVisibleTo($"PresentationCore.Tests, PublicKey={BuildInfo.WCP_PUBLIC_KEY_STRING}")]
@@ -9,6 +9,7 @@
 using System.Diagnostics;
 using System.Globalization;
 using System.Windows.Automation;
+using System.Windows.Automation.Provider;
 using System.Windows;
 using Accessibility;
 using System.Runtime.InteropServices;
@@ -295,6 +296,82 @@ internal static Accessible Wrap(IAccessible acc, int idChild)
         internal bool   IsFocused          { get { return HasState(AccessibleState.Focused); } }
         internal bool   IsOffScreen        { get { return HasState(AccessibleState.Offscreen); } }
 
+        internal object GetPatternProvider(int patternId)
+        {
+            return GetPatternProvider(AccessibleExProvider, patternId);
+        }
+
+        internal object GetPropertyValue(int propertyId)
+        {
+            return GetPropertyValue(AccessibleExProvider, propertyId);
+        }
+
+        internal static object GetPatternProvider(IRawElementProviderSimple provider, int patternId)
+        {
+            if (provider == null)
+            {
+                return null;
+            }
+
+            try
+            {
+                return provider.GetPatternProvider(patternId);
+            }
+            catch (Exception e) when (IsAccessibleExUnavailable(e))
+            {
+                return null;
+            }
+        }
+
+        internal static object GetPropertyValue(IRawElementProviderSimple provider, int propertyId)
+        {
+            if (provider == null)
+            {
+                return null;
+            }
+
+            try
+            {
+                return provider.GetPropertyValue(propertyId);
+            }
+            catch (Exception e) when (IsAccessibleExUnavailable(e))
+            {
+                return null;
+            }
+        }
+
+        internal static IRawElementProviderSimple GetAccessibleExProvider(UnsafeNativeMethods.IServiceProvider serviceProvider, int childId)
+        {
+            if (serviceProvider == null)
+            {
+                return null;
+            }
+
+            try
+            {
+                Guid serviceId = typeof(UnsafeNativeMethods.IAccessibleEx).GUID;
+                Guid interfaceId = serviceId;
+                UnsafeNativeMethods.IAccessibleEx accessibleEx =
+                    serviceProvider.QueryService(ref serviceId, ref interfaceId) as UnsafeNativeMethods.IAccessibleEx;
+
+                if (accessibleEx == null)
+                {
+                    return null;
+                }
+
+                if (childId != NativeMethods.CHILD_SELF)
+                {
+                    accessibleEx = accessibleEx.GetObjectForChild(childId);
+                }
+
+                return accessibleEx as IRawElementProviderSimple;
+            }
+            catch (Exception e) when (IsAccessibleExUnavailable(e))
+            {
+                return null;
+            }
+        }
+
         internal Accessible FirstChild      
         { 
             get 
@@ -1391,6 +1468,19 @@ private static bool HandleIAccessibleException(Exception e)
             return true;
         }
 
+        private static bool IsAccessibleExUnavailable(Exception e)
+        {
+            COMException comException = e as COMException;
+            return e is ArgumentException
+                || e is InvalidCastException
+                || e is NotImplementedException
+                || comException != null
+                    && (comException.ErrorCode == NativeMethods.E_FAIL
+                        || comException.ErrorCode == NativeMethods.E_NOINTERFACE
+                        || comException.ErrorCode == NativeMethods.E_NOTIMPL
+                        || comException.ErrorCode == NativeMethods.E_INVALIDARG);
+        }
+
         // IAccessibles that we get from Winforms apps in partial trust return failure
         // code for some methods - notably accNavigate and accChild. The operation will
         // succeed, however, if we first navigate up to the parent, and then back down
@@ -1476,9 +1566,25 @@ private enum NavDir
         private IAccessible _acc;   // a full IAccessible object or an IAccessible parent that is managing a ChildID
         private int _idChild;       // this is ChildID which is the ID a server gives this child (not related to child order!)
         private int _accessibleChildrenIndex;    // this is how many children to skip over when calling AccessibleChildren
+        private bool _accessibleExProviderInitialized;
+        private IRawElementProviderSimple _accessibleExProvider;
 
         private IntPtr _hwnd;
 
+        private IRawElementProviderSimple AccessibleExProvider
+        {
+            get
+            {
+                if (!_accessibleExProviderInitialized)
+                {
+                    _accessibleExProvider = GetAccessibleExProvider(_acc as UnsafeNativeMethods.IServiceProvider, _idChild);
+                    _accessibleExProviderInitialized = true;
+                }
+
+                return _accessibleExProvider;
+            }
+        }
+
         #endregion Private Fields
     }
 }
@@ -24,7 +24,13 @@ internal class MSAAEventDispatcher : MSAAWinEventWrap
         #region Constructors
 
         private MSAAEventDispatcher()
-            : base(NativeMethods.EVENT_OBJECT_CREATE, NativeMethods.EVENT_OBJECT_ACCELERATORCHANGE)
+            : base(
+                NativeMethods.EVENT_OBJECT_CREATE,
+                NativeMethods.EVENT_OBJECT_ACCELERATORCHANGE,
+                ExpandCollapsePattern.ExpandCollapseStateProperty.Id,
+                ExpandCollapsePattern.ExpandCollapseStateProperty.Id,
+                TogglePattern.ToggleStateProperty.Id,
+                TogglePattern.ToggleStateProperty.Id)
         { }
 
         #endregion Constructors
@@ -179,6 +185,13 @@ internal override void WinEventProc(int eventId, IntPtr hwnd, int idObject, int
                 // get the 2-nd level table of events and properties we are listening for in this window
                 Hashtable eventTable = (Hashtable)_hwndTable[hwnd];
 
+                AutomationProperty property = GetPatternPropertyFromWinEvent(eventId);
+                if (property != null)
+                {
+                    MaybeFirePropertyChangeEvent(null, property, eventTable, hwnd, idObject, idChild, true);
+                    return;
+                }
+
                 switch (eventId)
                 {
                     case NativeMethods.EVENT_OBJECT_CREATE:
@@ -242,6 +255,18 @@ internal override void WinEventProc(int eventId, IntPtr hwnd, int idObject, int
 //                        break;
                 }
             }
+
+        }
+
+        internal static AutomationProperty GetPatternPropertyFromWinEvent(int eventId)
+        {
+            if (eventId == ExpandCollapsePattern.ExpandCollapseStateProperty.Id)
+                return ExpandCollapsePattern.ExpandCollapseStateProperty;
+
+            if (eventId == TogglePattern.ToggleStateProperty.Id)
+                return TogglePattern.ToggleStateProperty;
+
+            return null;
         }
 
         #endregion Internal Methods

@@ -486,6 +486,10 @@ ProviderOptions IRawElementProviderSimple.ProviderOptions
 
         object IRawElementProviderSimple.GetPatternProvider(int patternId)
         {
+            object provider = _acc.GetPatternProvider(patternId);
+            if (provider != null)
+                return provider;
+
             AutomationPattern pattern = AutomationPattern.LookupById(patternId);
             //Debug.WriteLine.WriteLine(string.Format(CultureInfo.CurrentCulture, "{0} IRawElementProviderSimple.GetPatternProvider {1}", this, pattern));
 
@@ -495,6 +499,10 @@ object IRawElementProviderSimple.GetPatternProvider(int patternId)
 
         object IRawElementProviderSimple.GetPropertyValue(int propertyId)
         {
+            object value = _acc.GetPropertyValue(propertyId);
+            if (value != null)
+                return value;
+
             AutomationProperty idProp = AutomationProperty.LookupById(propertyId);
             //Debug.WriteLine.WriteLine(string.Format(CultureInfo.CurrentCulture, "{0} IRawElementProviderSimple.GetPropertyValue {1}", this, idProp));
 
@@ -669,7 +677,13 @@ IRawElementProviderSimple ISelectionItemProvider.SelectionContainer
             {
                 //Debug.WriteLine.WriteLine(string.Format(CultureInfo.CurrentCulture, "{0} ISelectionItemProvider.SelectionContainer", this));
 
-                return IsRoot ? null : Parent;
+                MsaaNativeProvider parent = IsRoot ? null : Parent;
+                while (parent != null && !parent.IsPatternSupported(SelectionPattern.Pattern))
+                {
+                    parent = parent.IsRoot ? null : parent.Parent;
+                }
+
+                return parent;
             }
         }
         #endregion ISelectionItemProvider
@@ -880,6 +894,10 @@ protected virtual object GetPatternProvider(AutomationPattern pattern)
         // overridable implementation of IRawElementProviderSimple.GetPropertyValue
         protected virtual object GetPropertyValue(AutomationProperty idProp)
         {
+            object patternValue = GetPatternPropertyValue(this, idProp);
+            if (patternValue != null)
+                return patternValue;
+
             // The following UIA properties need support: AcceleratorKeyProperty, AccessKeyProperty, AutomationIdProperty, 
             // HasKeyboardFocusProperty, IsContentElementProperty, IsControlElementProperty, IsKeyboardFocusableProperty, 
             // IsPasswordProperty, IsReadOnlyProperty, NativeObjectModelAccessProperty, SiblingIdProperty, TabIndexProperty?, 
@@ -907,6 +925,7 @@ protected virtual object GetPropertyValue(AutomationProperty idProp)
                 else
                     return null;
             }
+
             else if (idProp == AutomationElement.IsEnabledProperty)
             {
                 return _acc.IsEnabled;
@@ -953,6 +972,24 @@ protected virtual object GetPropertyValue(AutomationProperty idProp)
             return null;
         }
 
+        internal static object GetPatternPropertyValue(IRawElementProviderSimple provider, AutomationProperty property)
+        {
+            if (property == ExpandCollapsePattern.ExpandCollapseStateProperty)
+            {
+                IExpandCollapseProvider expandCollapse =
+                    provider.GetPatternProvider(ExpandCollapsePattern.Pattern.Id) as IExpandCollapseProvider;
+                return expandCollapse?.ExpandCollapseState;
+            }
+
+            if (property == TogglePattern.ToggleStateProperty)
+            {
+                IToggleProvider toggle = provider.GetPatternProvider(TogglePattern.Pattern.Id) as IToggleProvider;
+                return toggle?.ToggleState;
+            }
+
+            return null;
+        }
+
         // overridable method used by value pattern to retrieve the value.
         protected virtual string GetValue()
         {
@@ -1309,7 +1346,9 @@ public CtrlTypePatterns(ControlType ctrlType, params AutomationPattern[] pattern
             new CtrlTypePatterns(ControlType.RadioButton, SelectionItemPattern.Pattern),
             // ControlType.Slider: it is impossible to tell which of RangeValue or Selection patterns to support so we're not supporting either.
             // ControlType.Spinner: it is impossible to tell which of RangeValue or Selection patterns to support so we're not supporting either.
-            new CtrlTypePatterns(ControlType.SplitButton, InvokePattern.Pattern)
+            new CtrlTypePatterns(ControlType.SplitButton, InvokePattern.Pattern),
+            new CtrlTypePatterns(ControlType.Tree, SelectionPattern.Pattern),
+            new CtrlTypePatterns(ControlType.TreeItem, SelectionItemPattern.Pattern)
         };
 
         private Accessible _acc; // the IAccessible we are representing. use Accessible to access.

@@ -27,12 +27,14 @@ internal class MSAAWinEventWrap
 
         #region Constructors
 
-        // ctor that takes a range of events
-        internal MSAAWinEventWrap(int eventMin, int eventMax)
+        // ctor that takes one or more event ranges as min/max pairs
+        internal MSAAWinEventWrap(params int[] eventRanges)
         {
-            _eventMin = eventMin;
-            _eventMax = eventMax;
-            _hHooks = new IntPtr[1];
+            if (eventRanges == null || eventRanges.Length == 0 || eventRanges.Length % 2 != 0)
+                throw new ArgumentException(SR.InvalidParameter);
+
+            _eventRanges = (int[])eventRanges.Clone();
+            _hHooks = new IntPtr[eventRanges.Length / 2];
             Init();
         }
 
@@ -74,12 +76,21 @@ internal void StartListening()
         {
             _fBusy = true;
 
+            for (int i = 0; i < _hHooks.Length; i++)
             {
-                // in a single hook, listen for a range of WinEvent types
-                _hHooks[0] = Misc.SetWinEventHook(_eventMin, _eventMax, IntPtr.Zero, _winEventProc, 0, 0, _fFlags);
-                if (_hHooks[0] == IntPtr.Zero)
+                int rangeIndex = i * 2;
+                _hHooks[i] = Misc.SetWinEventHook(
+                    _eventRanges[rangeIndex],
+                    _eventRanges[rangeIndex + 1],
+                    IntPtr.Zero,
+                    _winEventProc,
+                    0,
+                    0,
+                    _fFlags);
+                if (_hHooks[i] == IntPtr.Zero)
                 {
                     StopListening();
+                    return;
                 }
             }
             _fBusy = false;
@@ -213,8 +224,7 @@ internal WinEvent(int eventId, IntPtr hwnd, int idObject, int idChild)
         }
 
         private Queue _qEvents;                // Queue of events waiting to be processed
-        private int _eventMin;                 // minimum WinEvent type in range
-        private int _eventMax;                 // maximium WinEventType in range
+        private int[] _eventRanges;            // pairs of minimum and maximum WinEvent types
         private IntPtr [] _hHooks;             // the returned handles(s) from SetWinEventHook
         private bool _fBusy;                   // Flag indicating if we're busy processing
         private int _fFlags;                   // SetWinEventHook flags

@@ -1140,6 +1140,7 @@ internal static int LODWORD(long n)
 
         internal const int E_ACCESSDENIED = unchecked((int)0x80070005);
         internal const int E_FAIL = unchecked((int)0x80004005);
+        internal const int E_NOINTERFACE = unchecked((int)0x80004002);
         internal const int E_UNEXPECTED = unchecked((int)0x8000FFFF);
         internal const int E_INVALIDARG = unchecked((int)0x80070057);
         internal const int E_MEMBERNOTFOUND = unchecked((int)0x80020003);

@@ -8,6 +8,7 @@
 using System.Runtime.InteropServices;
 using System.Text;
 using System.Diagnostics;
+using System.Windows.Automation.Provider;
 using NativeMethodsSetLastError = MS.Internal.UIAutomationClientSideProviders.NativeMethodsSetLastError;
 
 namespace MS.Win32
@@ -79,6 +80,28 @@ internal static class UnsafeNativeMethods
         internal static Guid IID_IDispatch = new Guid(0x00020400, 0x0000, 0x0000, 0xC0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x46);
         internal static Guid IID_IAccessible = new Guid(0x618736e0, 0x3c3d, 0x11cf, 0x81, 0x0c, 0x00, 0xaa, 0x00, 0x38, 0x9b, 0x71);
 
+        [ComImport, Guid("6D5140C1-7436-11CE-8034-00AA006009FA"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
+        internal interface IServiceProvider
+        {
+            [return: MarshalAs(UnmanagedType.IUnknown)]
+            object QueryService(ref Guid service, ref Guid riid);
+        }
+
+        [ComImport, Guid("F8B80ADA-2C44-48D0-89BE-5FF23C9CD875"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
+        internal interface IAccessibleEx
+        {
+            [return: MarshalAs(UnmanagedType.Interface)]
+            IAccessibleEx GetObjectForChild(int idChild);
+
+            void GetIAccessiblePair([MarshalAs(UnmanagedType.Interface)] out IAccessible accessible, out int childId);
+
+            [return: MarshalAs(UnmanagedType.SafeArray, SafeArraySubType = VarEnum.VT_I4)]
+            int[] GetRuntimeId();
+
+            [return: MarshalAs(UnmanagedType.Interface)]
+            IAccessibleEx ConvertReturnedElement([MarshalAs(UnmanagedType.Interface)] IRawElementProviderSimple provider);
+        }
+
         [DllImport("oleacc.dll", SetLastError=true)]
         internal static extern IntPtr GetProcessHandleFromHwnd(IntPtr hwnd);
 
@@ -474,4 +497,3 @@ public struct LHITTESTINFO
         }
     }
 }
-
@@ -15,6 +15,7 @@
   </ItemGroup>
   <ItemGroup>
     <Compile Include="$(WpfSharedDir)RefAssemblyAttrs.cs" />
+    <Compile Include="LibraryAssemblyInfo.cs" />
     <Compile Include="$(WpfSharedDir)MS\Win32\NativeMethodsSetLastError.cs" />
     <Compile Include="$(WpfCommonDir)src\System\SR.cs">
       <Link>Common\System\SR.cs</Link>